Abstract

Reactive transport phenomena, in particular, the transport of contaminants, are of fundamental interest in environmental sciences. The presence of hazardous chemicals in the subsurface environment has become an important driving force to develop reactive transport models capable to predict their fate (Dagan 1989; Jury and Roth 1990; Sardin et al. 1991; Knox et al. 1993; Appelo and Postma 1996; Lichtner et al. 1996). These models represent the natural porous medium as two types of phases: (i) immobile solid phases and (ii) mobile liquid (and/or gaseous) phases. Depending on the affinity to the respective phases, chemical species distribute between the different phases and the corresponding phase boundaries. Accordingly, the transport of chemicals is dictated by partitioning of the mobile dissolved species and the stationary species adsorbed to the solid phase. Distribution into the solid phases and interfacial reactions result in a reduction of the dissolved contaminant concentrations in the liquid phase, and accordingly in a slow-down of the contaminant spreading.